1. Field of the Invention
This invention relates to a blood collection device for use in chemistry studies. More particularly, the present invention pertains to a blood collection device comprising an additive particle formulation, which formulation has combined antiglycolysis and anticoagulation properties.
2. Description of the Related Art
In carrying out blood collection, centrifuging and measurement of the blood sugar value for a specimen, a series of steps are required. Since the steps required are time consuming due to the increased complexity of the collection and testing work efficiency tends to be poor.
When blood is allowed to remain in a tube after being collected, the blood sugar value of the specimen declines with the passage of time because of glycolysis, that is, consumption of the sugar component by the cells in the blood. Therefore, an additive or reagent for inhibiting glycolysis in blood that is collected and stored for a period of time prior to testing is needed.
A typical antiglycolytic agent, sodium fluoride has been used to reduce glycolysis in blood. Sodium fluoride is associated with antiglycolytic action as well as hemolytic toxicity and anticoagulant activity.
However, the anticoagulant activity of the sodium fluoride is not sufficient at the low additive levels required for antiglycolytic action and averting hemolysis. Therefore the blood sample treated with sodium fluoride only is not suitable for the analysis of the sugar content by methods affected by hemolysis in the plasma. Therefore, sodium fluoride used as an anticoagulant agent limits the subsequent method of blood sugar analysis. To remedy the shortcoming of sodium fluoride, another component could be combined with the sodium fluoride so as to form an additive formulation for use in blood collection devices. A low hemolytic toxicity type of component is desirable for the anticoagulant, since hemolysis in the specimen will affect the glucose values.
Freeze drying, vacuum drying, liquid filing and powder filling are the conventional methods for filling additive formulations into blood collection devices. However, these conventional methods have disadvantages. In the case of freeze-drying, additive formulations can be rehydrated again after drying, which is not desirable. With drying methods, the additive formulations tend to be localized within the tube. Also, vacuum drying process may adversely affect the dissolution characteristics of the additives.
Powder filling of formulations is currently used to produce additives, that have more than two (2) components, wherein the components are dry blended before filling into the tube. However, it is very difficult to blend and fill because the component ratios vary due to the different specific gravity and particle size of each component. Powder mixing consists of siffting the components and then mixing in a high speed mixer. The result is a bulk powder mixture that is then dispensed into a tube. Each component separates from the other in the dry blended powder formulation by shock or vibration. As a result, the component ratio varies in each tube.
Liquid filling is not practical because of the low solubility of the antiglycolytic and anticoagulant components of the additives. Due to the low solubility, large liquid fills are required which reduce the glucose value of the resulting plasma sample by dilution. In addition, liquid filling is not practical because liquid additives are subject to permeation through plastic tubes which will lead to drying of the additive and poor dissolution characteristics.
A need has therefore been identified for solid additive formulations with improved fill and reduced hemolysis properties for blood collection devices. Blood collection tubes need to be designed in such a manner that additive fill formulations in tubes efficiently work in tests or analysis, and the formulations do not interfere with testing or analysis. Such tests include but are not limited to hematology, blood chemistry, blood typing, toxicology analysis and therapeutic drug monitoring.